Original description:
I’ve said most of what I’ve got for Rarity in my original My Little Maniraptor piece, so not much to say here. She’s a caenagnathid oviraptorosaur, if only to differentiate her from Twilight, an oviraptorid. She may not be able to form fancy curls with pennaceous feathers* the way the original Rarity does with her mane and tail, but you can be sure she keeps hers neat and well preened.
*Though with the power of artificial selection, this has been done in extant maniraptors